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Finding the Fourth Proportional to 1,420.62, 1,960.70 and 861.56

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Solution

The fourth proportional to 1,420.62, 1,960.70 and 861.56 is: 1,189.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.62 : 1,960.70 = 861.56 : x
  2. Step 2: Convert to fraction form
    1,420.62/1,960.70 = 861.56/x
  3. Step 3: Cross multiply
    1,420.62x = 1,960.70 × 861.56
  4. Step 4: Simplify right side
    1,420.62x = 1,689,253.93
  5. Step 5: Solve for x
    x = 1,689,253.93/1,420.62
  6. Step 6: Final answer
    x = 1,189.10

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.